The subject matter of the present invention relates generally to optical sighting apparatus for weapons such as hunting bows, and in particular, to a bow sight for viewing a target through a partial reflective mirror onto which is projected the image of a lighted reticle located outside the field of view of such target to provide an aiming spot of colored light superimposed over the image of the target. A light guide member transmits colored light through at least one aiming aperture in the reticle to provide the aiming spot. The bow sight apparatus of the present invention is especially useful for hunting bows used to shoot wild game with arrows, but may also be employed for stationary target shooting.
It has previously been proposed in U.S. Pat. No. 3,645,635 of Steck issued Feb. 29, 1977 and U.S. Pat. No. 3,897,158 of Steck issued July 29, 1975 to provide a sighting device for a firearm such as a shotgun employing a lighted reticle of fluorescent plastic material positioned outside the field of view of the sighting device for superimposing a lighted aiming spot over the image of the target viewed by such sighting device. The image of the reticle aiming spot is projected onto a partial reflecting mirror through which the image of the target is transmitted in order to superimpose such aiming spot on the image of the target. However, unlike the bow sight apparatus of the present invention, the lighted reticle aiming spot of such prior patents is formed by the entire output end of the fluorescent plastic member, such reticle member converting ambient light into fluorescent light of a different color such as red or orange. This limited the diameter or thickness of the reticle rod or plate to a range of 0.020 to 0.150 inch or less which reduced the lighting efficiency and necessitated increasing the side area of the reticle by providing a spiral shaped rod or a flat plate with a ball and socket corner connection. This problem is avoided in the present bow sight by employing a light guide whose output end overlaps one or more aiming apertures in the reticle member so that such light guide is of a larger cross sectional area than the aiming spots produced by such apertures and has greater lighting efficiency. In addition such prior sighting device includes internal windage and elevation adjustments but no adjustments for different target ranges or the use of multiple of aiming spots for different ranges in the manner of the present invention. In addition, the bow sight of the present invention employs an adjustable bow mount means for mounting the sight on a bow and for adjusting the bow sight vertically and horizontally to aim the bow which of course is not shown in such prior patents. The bow sight of the present invention is also more versatile in that it employs a range adjustment feature which moves the position of a single aiming spot on the target image to provide different ranges.
U.S. Pat. No. 3,700,339 of Steck issued Oct. 24, 1972 is also of interest as showing a gun sight for a firearm employing a fluorescent reticle mounted directly in the field of view of the target at the end of the barrel of a pistol or rifle. Such gun sight is not practical for a bow sight because the aiming reticle must be positioned several feet from the eye so as to obscure very little of the target image.
The bow sight apparatus of the present invention has several advantages including a lighted aiming spot of small size and high brightness for maximum visibility superimposed over the target image without obstructing the view of the target. In addition, the bow sight is more versatile in that it is provided with adjustable target range selection. In one embodiment a range adjustment from 20 to 40 yards is achieved by moving a single aiming spot. In another embodiment range adjustment is achieved with 3 different ranges provided by employing 3 spaced aiming spots which are distinguishable from one another, such as by their size or vertical position for dots of the same size.
The present bow sight has the added advantage of providing an extremely accurate sight by employing a bow mounting bracket which is adjustable vertically and horizontally in order to more accurately set the aiming spot on the point of impact of the arrow during calibration aiming in of the sight. With the present invention using a separate target viewer and a projected light reticle positioned outside the field of view of such viewer, a much wider field of view and sharp image focus are achieved. This also enables fast handling of the bow in the field for more productive hunting. Another advantage of the bow sight of the present invention is that a battery operated light source such as a light emitting diode (LED), may be employed to further increase the brightness of the aiming spot which may be desireable under low ambient light conditions. The LED light source and the fluorescent plastic material of the light guide may be selected to produce an aiming spot of the same green color light wavelength which is more easily reflected by the partial reflecting beam splitting mirror. In addition, such beam splitting mirror is mounted more accurately by slotted plastic mounting buttons on opposite sides thereof and to resist damage by means of resilient shock absorbing rubber mounting pads at the top and bottom of such mirror to prevent misalignment or breakage to the mirror during use.